the one thing I think Caterpillar nailed right with the hightrack is the angle of the lift rams . Nightmare to build sweeps for by the looks though . Fella retiring from a life time of contracting I bought some scrub rolling gear off said of the hightrack D4 that there's a hole to pull the transmission out of , real easy to work on and as he said it needed it . It also said of his Komatsu's that they are hard to work on but don't need much . Another point he was uncomplimentary on was the over-heating on the D4 , he said it was transmission related . He had fitted in front of the existing radiator another to simply lift cooling capacity that fixed the problem . Local D4E has an overheating problem to . Every thing has been pulled apart and checked to no avail , same capacity problem with the added disadvantage of not listening to those who can give them help .